<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>左右布局</title>
    <style>
        .border {
            border: 1px #1a6aab solid;
            box-sizing: border-box;
        }
        .container {
            position: relative;
        }

        /* position:fixed 为何不用？ */
        nav {
            position: absolute;
            left: 0;
            width: 200px;
        }

        section {
            margin-left: 200px;
            height: 200px;
        }

        footer {
            position: absolute;
            bottom: 0;
            left: 0;
            height: 70px;
            background-color: #00bbee;
            width: 100%;
        }

        body {
            margin-bottom: 120px;
        }
    </style>
</head>
<body>
<div class="container">
    <nav class="border"></nav>
    <section class="border"></section>
    <section class="border"></section>
    <section class="border"></section>
</div>


</body>
</html>